This invention relates to color concentrates for preparing colored synthetic fibers. It is more particularly directed to color concentrates containing unique deflocculating agents.
It is well known that synthetic fibers, particularly polyester fibers, are difficult and expensive to dye dark shades. To produce such dark synthetic fibers, it has been the practice in years past to add a pigment such as carbon black during the polymerization process. When this is done, the pigment is carried into the fiber-forming polymer itself, and consequently into the fiber.
This method has produced satisfactory fibers, but pigment added this way tends to quickly clog filters, particularly the sand-pack filters located before the spinning apparatus. Besides this, because of the nature of the process, the entire polymerization and spinning train becomes contaminated with pigment, or with dye if a dye is used, and if this equipment is then used to manufacture fiber of a different color, the whole apparatus must first be cleaned.
Repacking filters and cleaning apparatus mean that equipment lies idle while it is being worked on and this in turn means economic loss.
The color concentrates of this invention minimize these disadvantages. According to the invention, a color concentrate is added after the fiber-forming polymer has been prepared, so there is less equipment to clean. In addition, the color concentrate stabilizes the pigment so that there is far less filter clogging. For example, when carbon black is incorporated into a polyester fiber according to the invention, ordinary commercial sand-pack filters can be in continuous use for in excess of 18 days, while the same filter, used in a conventional process, clogs to the point of uselessness in only 4 days.
In addition to this, use of the color concentrates of the invention provides a fiber much less prone to break in winding-up or texturing.
The color concentrates provide all these advantages and, as a bonus, give fibers with more brilliant and stable colors than those fibers conventionally produced.